We have developed a variety of tasks to activate regions of interest in functional neuroimaging studies. 1. To examine the levels of processing account of episodic memory we devised a series or recognition memory tasks. We also paid special attention to the development of a control task that would not involve active processing so as to better observe hippocampal activation. Results indicate similar regions, including prefrotnal cortex, were activated during encoding and retrieval. Hippocampal activation was obtained in ana ROI aanalysis. 2. We assessed the role of COMT genotype in an fMRI study which gauged the effects of amphetamine on cortical efficiency. Sonsistent with an inverted u-shaped function, normal subjecs woith low dopaminergic tone (val genotype) improved frontal ortical processing, while subjects with the met genotype (high dopaminergic tone) showed diminsished cortical efficiency at high working memory loads. 3. We developed a carefully matched set of verbal fluency tasks to examine the relation between semantic processing, thought disorder, and neurophysiology in schizophrenia using PET CBF methods. We und an area in inferior prefrontal cortex that was more activated insemantic fluency and correlated with a classic symptom of schizophrenia -- thought disorder.